In my textbook it often says how you can (and should if you want to sound normal) often leave out nouns and pronouns just like in other languages when it is clear what is being talked about. Often times, I'm unsure how to do this.

For example:person 1: Can you pick up groceries?person 2: Yes, on the weekend.

So how can I simplify person 2's statement without being grammatically incorrect?

I would take off the きみは. If it's a one on one conversation there is no need to make clear whom you're talking to, right?

And if it was a casual conversation, I'd probably not use the "を します" at the end of the second sentence. Maybe end it with just a particle... (で?) But that's already too advanced for me... It would probably be agrammatical.